Barack Obama’s administration has ruled out drilling for oil and gas in the pristine Arctic Ocean, throwing up a last-ditch barrier to the pro-fossil fuels agenda of incoming president Donald Trump.

The US Department of the Interior said that the “fragile and unique” Arctic ecosystem would face “significant risks” if drilling were allowed in the Chukchi or Beaufort Seas, which lie off Alaska. It added that the high costs of exploration, combined with a low oil price, would probably deter fossil fuel companies anyway.

“The plan focuses lease sales in the best places – those with the highest resource potential, lowest conflict, and established infrastructure – and removes regions that are simply not right to lease,” said the interior secretary, Sally Jewell.

“Given the unique and challenging Arctic environment and industry’s declining interest in the area, forgoing lease sales in the Arctic is the right path forward.”

The move, announced as part of the federal government’s land and ocean leasing program that will run from 2017 to 2022, has been cheered by environmentalists who called for the Arctic to be put off limits for drilling to help slow climate change and avoid a catastrophic oil spill.

“Today’s announcement demonstrates a commitment to prioritizing common sense, economics and science ahead of industry favoritism and politics as usual,” said Jacqueline Savitz, Oceana’s senior vice-president for the United States.

“The decades-long push to drill in the Arctic has put this unique and diverse ecosystem at risk, cost tens of billions of dollars and created significant controversy without providing the promised benefits. We now have the opportunity to put the old arguments behind us and work together toward a sustainable future for the Arctic region.”

The removal of the Arctic Ocean from federal leasing runs contrary to Trump’s vow to “lift the Obama-Clinton roadblocks” to large fossil fuel projects and throw open vast areas of land and water to drilling. But even if Trump reverses the Arctic ban, the economics are still unfavorable for offshore drilling in the region.

Shell spent more than $7bn on its attempt to exploit oil and gas reserves in the Arctic after being allowed to do so by the US government despite a high predicted risk of an oil spill in the frigid ecosystem. The Anglo-Dutch company abandoned its drilling operation in September last year, having faced huge costs and fierce opposition from green groups.

Fossil fuel interests have eyed the Arctic as a huge new frontier for oil and gas riches, with rapidly melting sea ice making areas of the Arctic Ocean more accessible for drilling rigs. The Arctic holds about 90bn barrels of undiscovered oil and 30% of the world’s untapped natural gas.

However, the International Energy Agency has warned that the drilling in the Arctic is not yet commercially viable, while environmental groups have warned that opening up new fossil fuel development will push the planet over the precipice into catastrophic climate change.

The Arctic is at the forefront of global warming, with the region heating up at twice the rate of the rest of the planet. This summer, Arctic sea ice shrank to its second smallest extent ever recorded, with the annual winter regrowth occurring at a “sluggish” rate, according to the National Snow and Ice Data Center. On current trends, ice is returning at a slower rate than the record low experienced in 2012.

The new federal leasing plan also makes the Atlantic off-limits to drilling, another success for environmentalists and coastal communities that fought initial plans to lease areas to fossil fuel firms. But the plan does include 10 new sales in the Gulf of Mexico, the epicenter of US offshore drilling.

The federal government, through the Bureau of Ocean Energy Management, currently manages around 3,400 active oil and gas leases in federal waters, covering an area spanning 18m acres.

“Today’s decision is a victory for the Arctic and demonstrates the growing strength of the movement to keep fossil fuels in the ground. But we also need to protect communities along the Gulf of Mexico,” said Marissa Knodel, a campaigner at Friends of the Earth.

“Unfortunately, Donald Trump has made it clear that he wants to return to the days of ‘drill baby drill’. That’s why President Obama must use his remaining days in office to permanently keep as much of our lands and waters from Trump and his oil cronies as possible.”

The Obama administration has pushed through a number of climate-related measures since the election of Trump, who denies climate change exists and has promised to withdraw the US from the international effort to tackle it. The president-elect also proposes cutting all funding for clean energy and to dismantle Obama’s Clean Power Plan, the main policy designed to cut emissions.

This week, the department of the interior unveiled regulations to slash fugitive emissions of methane, a potent greenhouse gas, from natural gas operations. The US was also the first nation to submit to the United Nations a plan on how it will reduce emissions, with the Obama administration setting a goal of an 80% reduction by 2050.

John Kerry, the secretary of state, said this week that climate change is “bigger than one person, one president” and that international progress on the issue was unstoppable, despite the threat of US withdrawal from the Paris climate agreement.

Businesses have also stated their support for the international climate effort, with more than 360 companies, including Levi’s, Kellogg’s and Nike, urging Trump to keep up American efforts to ward off dangerous global warming.